Various systems that use a flowing fluid require a shutoff mechanism to stop the flow once the system's operation is complete. Common toilet tanks, for example, include a floater mechanism for controlling the flow of water into the toilet tank. The floater mechanism includes parts such as a flush valve, a float, and a fill valve. When functioning properly, after the toilet is flushed, the floater mechanism allows the water to fill the tank to a desired level and then shuts off the water flow. More specifically, after the flushing, the flush valve blocks the outflow of the water from the tank into the toilet bowl, causing the water to rise in the tank. The rising water level raises the float. When the water level in the tank reaches a desired level, the float causes the fill valve to stop the water inflow into the tank. Other systems that use water or some other fluid may also use some shutoff mechanism. Examples of such systems include a sprinkler, an irrigation system, or a pool filler.
The shutoff mechanism in many such systems, however, may break down for a variety of reasons. The floater mechanism, for example, may break down if one or more of its parts are defective, or when something interferes with the proper operation of the system. For example, the flush valve may fail to block the outflow, the float may fail to rise or shut the fill valve, or the fill valve may fail to stop the water inflow into tank. In such cases, the fluid flow may continue, resulting in damages (e.g., due to flooding) or waste (e.g., over consumption of water).